scholarly journals Distribution Law of Three Spontaneous Combustion Zones in the Goaf Area of a Fully Mechanized Working Face under High Ground Temperature

2021 ◽  
Vol 8 (2) ◽  
pp. 86-90
Author(s):  
Duolei Kuai
Keyword(s):  
Spontaneous Combustion ◽  
Middle Part ◽  
Ground Temperature ◽  
Oxidation Zone ◽  
Distribution Law ◽  
Fire Extinguishing ◽  
Working Face ◽  
O2 Concentration ◽  
Air Intake ◽  
Concentration Changes

To figure out the distribution law of three spontaneous combustion zones in the goaf area of fully mechanized working face under high ground temperature, this study took the 11501# fully mechanized mining face of Zhujixi Coal Mine as the research object, and employed software Fluent to perform numerical simulations on the O2 concentration distribution in the goaf; then, combining with the actual situations on the site, the high-location boreholes and grout holes of the roof gas drainage roadway of the 11501# working face were selected as measuring points to measure the O2 concentration changes in a few positions such as in middle part of the goaf, on the air intake side, and on the air return side. The results show that, the numerical simulation results were basically consistent with the field measurement results, in the middle part of the goaf, the scope of the oxidation zone was 26.4m-62m; on the air intake side, the scope of the oxidation zone was 32m-96m; on the air return side, the scope of the oxidation zone was 28.4m-91m. The research findings of this paper provided a scientific reference for formulating fire-prevention and fire-extinguishing technical plans for mines.

scholarly journals Oxygen Distribution and Air Leakage Law in Gob of Working Face of U+L Ventilation System

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Xiaowei Zhai ◽  
Bo Wang ◽  
Shangrong Jiang ◽  
Weixia Zhang
Keyword(s):  
Oxygen Concentration ◽  
Spontaneous Combustion ◽  
Ventilation System ◽  
Burial Depth ◽  
Air Leakage ◽  
Coal Spontaneous Combustion ◽  
Working Face ◽  
Air Intake ◽  
And Control ◽  
The Relationship

In order to prevent and control coal spontaneous combustion effectively in the gob of U+L working face, the 30105 working face of Hanglaiwan mine was taken as the research object. The relationship models between oxygen concentration and burial depth of the two tunnels in the gob of U+L working face were established. The distribution of oxygen in the gob of the working face of U+L ventilation system was studied by field observation combined with numerical simulation. The results show that the air leakage in the gob is serious. There are a number of fluctuation areas where the oxygen concentration first decreases and then increases in the air intake side of the gob. The oxygen concentration peaked at 100m, 175m, and 245m, respectively, from the intake side of the gob. In the same position of the gob depth, the air leakage intensity on the intake side is generally higher than that on the return side, and the oxygen concentration on the intake side of the gob is slower than the return side. Oxygen concentration maintains at 5.09% when the depth of gob reaches 400m. Measures to prevent coal spontaneous combustion should be strengthened in the air intake side.

Research on ‘Three Zones’ of Goaf Spontaneous Combustion with U+L Ventilation

2014 ◽  
Vol 598 ◽  
pp. 753-757
Author(s):  
Yu Xin Zhao ◽  
Chang Hua Chen ◽  
Fei He ◽  
Jun Wen Li
Keyword(s):  
Numerical Simulation ◽  
Spontaneous Combustion ◽  
Great Influence ◽  
Ventilation Mode ◽  
Distribution Law ◽  
Air Volume ◽  
Working Face

In order to study “three zones” of goaf spontaneous combustion with U+L ventilation mode working face. Numerical simulation is used to simulate the distribution law of “three zones” of goaf spontaneous combustion in case of different distance between crossheading and working face, and different air quantity. Research suggests that the “three-zones” of spontaneous combustion has great influence with different distances and different supplied air volume.

scholarly journals Distribution law for the danger area for spontaneous coal combustion in a dynamic goaf with low air leakage speed

2020 ◽  
pp. 308-308
Author(s):  
Qiuling Zuo ◽  
Jingshan Li ◽  
Yujie Wang
Keyword(s):  
Coal Combustion ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Distribution Area ◽  
Air Leakage ◽  
Exponential Relationship ◽  
Working Face ◽  
Spontaneous Coal Combustion ◽  
Mining Face ◽  
The Relationship

This paper examines the relationship between the advancement of the working face and the distribution of spontaneous coal combustion under a low air leakage wind speed in a goaf. Based on the unsteady state simulation method, the process of spontaneous coal combustion was simulated in a fully mechanized coal mining face at different advancing speeds. The relationship between different advancing speeds and the distribution area of the oxidation zone of spontaneous coal combustion in a goaf was clarified. A safe advancing speed was determined. Furthermore, the advancement of the working face altered the area of spontaneous high temperature inside the goaf. An increase in the advancing speed increased the length of time of spontaneous combustion in the leftover coal. An exponential relationship was demonstrated between the spontaneous combustion area and the advancement of the fully mechanized mining face. When the oxygen concentration was used as a calculation indicator, the width of the oxidation zone was asymmetrical on the inlet and outlet, and the advancing distance of the working surface increased when the distance was shorter than 90 m and the return side was smaller than the inlet side. When the advancing distance was longer than 90 m, the width of the spontaneous combustion oxidation zone distribution remained unchanged. The study clarified the relationship between the distribution of the danger area for spontaneous coal combustion and advancing speed. This could provide a theoretical basis for the prevention and control technology of the spontaneous combustion of broken coal in a dynamic goaf.

Effect Analysis of Nitrogen Injection on the Variation of “Oxidation Zone” in Coal Mine Gob Based on Numerical Simulation

2016 ◽  
Vol 9 (1) ◽  
pp. 47-54
Author(s):  
Jing Shen ◽  
Mingran Chang
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Heat Dissipation ◽  
Spontaneous Combustion ◽  
Oxidation Zone ◽  
Effect Analysis ◽  
Mine Fire ◽  
Nitrogen Injection ◽  
The Difference ◽  
Residual Coal

One of the main reasons for coal mine fire is spontaneous combustion of residual coal in gob. As the difference of compaction degree of coal and rock, the underground gob can be considered as a porous medium and divided into “three zones” in accordance with the criteria. The “three zones” are “heat dissipation zone”, “oxidation zone” and “choking zone”, respectively. Temperature programming experiments are taken and numerical simulation with obtained experimental data is utilized to analyze the distribution of “three zones” in this paper. Different width and depth of “oxidation zone” are obtained when the inlet air velocity is changed. As the nitrogen injection has inhibition effect on spontaneous combustion of residual coal in gob, nitrogen is injected into the gob. The widths of “oxidation zone” are compared before and after nitrogen injection. And ultimately the optimum location and volume of nitrogen injection are found out.

The Pre-Controlling Technology of Spontaneous Combustion in Gutter-Up Gob for Fully Mechanized Top-Coal Caving Face

2013 ◽  
Vol 634-638 ◽  
pp. 3688-3695 ◽  
Author(s):  
Yang Xiao ◽  
Shu Gang Li ◽  
Jun Deng ◽  
Xu Wang
Keyword(s):  
Carbon Dioxide ◽  
High Temperature ◽  
Fly Ash ◽  
Coal Mining ◽  
Spontaneous Combustion ◽  
Good Effect ◽  
Air Leakage ◽  
Coal Spontaneous Combustion ◽  
Liquid Carbon ◽  
Fire Extinguishing

In China, as popularizing the technology of fully mechanized top-coal mining and increasing the strength and depth of mining, the gutter-up gob can be formed. But the work of fire preventing and extinguishing for its coal spontaneous combustion is more complexity and difficulty. In this paper, based on geology parameters and mining practice for 93up12 fully mechanized top-coal caving face in Nantun coalmine, the form and character of gutter-up gob are analyzed. According to the hidden danger of high temperature for spontaneous combustion in the gob, we adopt the comprehension technologies of fire extinguishing and preventing which include sealing air-leakage, grouting, and injecting compound gel with fly-ash, foam of retarding oxidation, liquid carbon dioxide, and gas of nitrogen. By putting in practice the pre-controlling technology in gutter-up gob and monitoring data of target gases, it obtains a good effect and ensures the safety in production of the fully-mechanized top-coal caving face.

The current state of the problem of predicting spontaneous combustion and explosiveness of sulfide ores and host rocks at a depth of more than 1500 m.

2021 ◽  
pp. 77-80
Author(s):  
Z.G. Ufatova
Keyword(s):  
Moisture Content ◽  
Air Temperature ◽  
Initial Phase ◽  
Spontaneous Combustion ◽  
Fire Hazard ◽  
Free Access ◽  
Sulfide Ores ◽  
Working Face ◽  
Time In Treatment ◽  
Endogenous Fire

The mining factors of ore fire hazard during mining of the lower horizons of the Oktyabrskiy and Talnakhskiy northern deposits are considered. It is noted that the probability of self-heating of sulfide ores and the sulfide dust’s tendency to spontaneous combustion and explosiveness in certain sections of rich sulfide copper-nickel ores are quite high. The oxidation of sulfide ores occurs continuously due to the absorption of oxygen from the mine atmosphere and is accompanied by the release of heat. The oxidation can be accompanied by intense heating of the ore in mining conditions, with the accumulation of large volumes of broken rock mass for a long time in treatment and preparation workings and with free access of air to the bulk of the ore mass. The processes of ore and rock oxidation are especially intense when their moisture content is 1–4%. When the ore is heated above 35 °C, sulfurous gas (SO2) may be released. The main signs of the above-mentioned oxidative processes’ development and signs of the initial phase of a possible underground endogenous fire are indicated along with a constant increase in the temperature of the air coming from the bottom of the face. It is noted that in case of detecting at least one of the signs of a possible underground endogenous fire’s initial phase, urgent measures are taken to improve the ventilation of this working face, to ensure maximum intensity of shipped ore from the fresh stream and the content of sulfurous gas and hydrogen sulfide and mine air temperature are determined every 4 hours. If after two days on the outgoing stream there is no decrease in the content of sulfur dioxide and air temperature, then it should be considered that an endogenous fire has occurred. Measures for the prevention, localization and elimination of foci of spontaneous combustion are given. As an additional safety measure, it is recommended to moisten the dust, since sulfide dust becomes non-explosive at a moisture content of 9–9,5%, and at a humidity of 10% the dust does not transmit an explosive impulse.

scholarly journals Safe and Efficient Coal Mining Below the Goaf: A Case Study

Energies ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 864 ◽  
Author(s):  
Weidong Pan ◽  
Shaopeng Zhang ◽  
Yi Liu
Keyword(s):  
Abutment Pressure ◽  
Theoretical Calculations ◽  
Distribution Law ◽  
Working Face ◽  
Strata Behavior ◽  
Working Resistance ◽  
Behavior Characteristics ◽  
Theoretical Analyses ◽  
Important Significance

Mining at the fully mechanized working face below the goaf of the short-distance coal seam is influenced by the upper goaf. To address this problem, methods such as theoretical analyses, numerical simulation, and on-site measurement are used to study the strata behavior characteristics of the Ningxia Lingxin Coal Mine 051508 working face in this study. The roof weighting intervals of the working faces below the goaf and the non-goaf are obtained via theoretical calculations. The stoping processes of the working faces below the goaf and the non-goaf are simulated with FLAC3D to obtain the distribution law of the bearing pressure and plastic zones before the working face. Based on the statistical analysis of the measured working resistance of the supports and its distribution, the roof weighting interval of the working face mining below the goaf is obtained. The results show that the roof weighting interval and the advanced abutment pressure during mining at the working face below the goaf are smaller than those below the non-goaf, providing a reasonable theoretical basis for mining below the goaf, and having important significance for safe and efficient mining.

scholarly journals Study on Flow Field and Rotor Safety Characteristics of MSPs Based on Flow Thermo-Coupling

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 711
Author(s):  
Yiming Chen ◽  
Rongsheng Zhu ◽  
Yonggang Lu ◽  
Zhenjun Gao ◽  
Junjun Kang
Keyword(s):  
High Temperature ◽  
Equivalent Stress ◽  
Outer Edge ◽  
Cover Plate ◽  
Distribution Law ◽  
Maximum Deformation ◽  
Structural Intensity ◽  
Operation Conditions ◽  
Working Face ◽  
Different Temperatures

In order to obtain the structural intensity under the operation conditions of MSP (molten salt pump), the rotor component of MSP is taken as the research object. In this paper, the influence of material properties change on the structural performance of MSP at different temperatures is analyzed. The stress distribution and strain distribution of MSP rotor components under different loads are investigated, and the intensity calculation of MSP rotor system is carried out to explore whether it meets the intensity requirements under high temperature operation, which lays a foundation for the high temperature test of MSP. The results show that the maximum deformation position of the blade working face appears at the outer edge of the impeller. When the fluid-structure coupling is applied, the blade strain law and the strain law during thermo-coupling are similar. The effect of the temperature field on the degree of blade deformation is not significant, provided that other factors remain the same. The position where the impeller equivalent stress is the largest is mainly concentrated in the area where the blade is in contact with the front and rear cover plates at the outlet of the impeller. Different degrees of stress concentration occur in the area where the blade is in contact with the impeller hub. The distribution law of the equivalent stress on the surface of the impeller cover plate is that the equivalent stress value changes periodically along the circumferential direction of the impeller, and the number of change cycles is equal to the number of impeller blades. This study can provide a reference for the structural design of MSPs.

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